OLED Common Voltage Line Reaction Blocking Part
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Solution Overview
Problem
In OLED displays, a galvanic reaction occurs between the materials of the common voltage line and the pixel electrode during the etching process, leading to corrosion and dark point defects due to the exposure of the common voltage line to electrolytes, which increases electrical resistance and reduces the display's reliability.
Innovation Solution
A reaction blocking part, made of the same material as the pixel electrode, is used to cover and protect the common voltage line in the peripheral area, preventing exposure and contact with the pixel electrode during the etching process, thereby blocking the galvanic reaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the common voltage line is exposed in the peripheral area, then the etching process can access the pixel electrode, but galvanic reaction occurs between the common voltage line and pixel electrode materials causing corrosion and dark point defects
Solution Approach 1:
The patent divides the peripheral area into multiple regions: a first region where the protective layer is removed to expose the common voltage line for etching access, and a second region where the protective layer remains to prevent galvanic reaction. This spatial segmentation allows the etching process to access the pixel electrode while simultaneously protecting against corrosion in other areas.
Solution Approach 2:
The protective layer is selectively removed only in the first region of the peripheral area, creating different protective qualities in different locations. The second region maintains full protective coverage to prevent galvanic reaction, while the first region allows controlled exposure for manufacturing purposes. This local differentiation resolves the contradiction between manufacturing access and reliability.
2Reliability
If the common voltage line is completely covered by protective layer, then galvanic reaction is prevented, but etching process cannot access the pixel electrode
Solution Approach 1:
The protective layer coverage is segmented into two distinct zones: complete coverage in the second region to prevent galvanic reaction, and selective removal in the first region to enable etching access. This segmentation allows both corrosion prevention and manufacturing accessibility to be achieved simultaneously in different locations.
Solution Approach 2:
Different protective qualities are applied to different regions of the peripheral area. The second region has full protective layer coverage for maximum corrosion prevention, while the first region has reduced coverage to allow etching access. This local quality differentiation resolves the contradiction between complete protection and manufacturing access.
3Reliability
If materials of common voltage line and pixel electrode are in contact with electrolyte, then electrical connection is established, but galvanic reaction causes corrosion and increases electrical resistance
Solution Approach 1:
The harmful element (electrolyte exposure) is extracted or removed from the system by selectively removing the protective layer only in the first region where controlled exposure is needed for etching. The second region maintains protective layer coverage to extract/remove the electrolyte from contact with the common voltage line, thereby eliminating galvanic reaction while preserving necessary electrical connections.
Solution Approach 2:
The protective layer serves as an intermediary barrier between the common voltage line and the electrolyte. By selectively removing this intermediary in the first region, controlled access is provided where needed, while maintaining the intermediary protection in the second region to prevent harmful galvanic reaction. The intermediary thus mediates between electrical connection requirements and corrosion prevention.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively reduces or prevents corrosion of the pixel electrode, minimizing dark point defects and maintaining the electrical integrity of the OLED display by blocking the galvanic reaction between the common voltage line and the pixel electrode materials.
Implementation Method 1
a galvanic reaction occurs between the materials of the common voltage line and the pixel electrode during the etching process
Data Source
AI summary
An organic light emitting diode (“OLED”) display includes: a substrate divided into a pixel area, and a peripheral area enclosing the pixel area; an OLED in the pixel area and including a first electrode, an organic emission layer and a second electrode; a common voltage line in the peripheral area and transmitting a common voltage to the second electrode; and a reaction blocking part overlapping the common voltage line.